Problem: Which of the following numbers is a multiple of 5? ${50,52,68,93,103}$
Answer: The multiples of $5$ are $5$ $10$ $15$ $20$ ..... In general, any number that leaves no remainder when divided by $5$ is considered a multiple of $5$ We can start by dividing each of our answer choices by $5$ $50 \div 5 = 10$ $52 \div 5 = 10\text{ R }2$ $68 \div 5 = 13\text{ R }3$ $93 \div 5 = 18\text{ R }3$ $103 \div 5 = 20\text{ R }3$ The only answer choice that leaves no remainder after the division is $50$ $ 10$ $5$ $50$ We can check our answer by looking at the prime factorization of both numbers. Notice that the prime factors of $5$ are contained within the prime factors of $50$ $50 = 2\times5\times5 5 = 5$ Therefore the only multiple of $5$ out of our choices is $50$. We can say that $50$ is divisible by $5$.